Lesson14 Dolphins

Many people have experienced the joy of standing on a moving ship and watching a group of dolphins swim alongside. Dolphins are not only playful animals but they are also highly intelligent. They are mammals that can be found in most of the world's oceans as well as in fresh water.
Dolphins can swim at speeds of up to 56 KPH and they can dive to depths of 200 meters and stay underwater for 5-8 minutes without resurfacing for air.

They are well-known for the unique clicking sound they use like sonar to locate food as well as obstacles. Every dolphin has its distinctive individual whistling sound used for communication.
When dolphins sleep, they sleep in a semi-alert state by resting one side of their brain at a time. They will help sick or injured dolphins as much as they can, and they act as a team if there is danger.
It is because of these and other human-like qualities that people have a special feeling for dolphins.

dolphin ? 海豚
mammal ? 哺乳動物
resurface ? 重新露面
unique ? 獨特的
sonar ? 聲波定位儀
obstacle ? 障礙物
distinctive ? 與眾不同的
whistle ? 吹口哨
semi-alert ? 半警惕的

海豚

許多人一定會有這樣開心的經歷——站在航行的船上，看著一群海豚從旁邊游過。海豚不僅是一種有趣的動物而且極其聰明。海豚是哺乳動物，人們可以在世界上大多數的海洋和淡水中找到它。
海豚的游速可以達到每小時五十六公里，可以潛到兩百米深的地方，在水下待五到八分鐘而不浮出水面。海豚另一有名的特點是它們可以使用獨特的像聲波定位器一樣的敲擊聲來確定食物和障礙物的位置。每一頭海豚都有自己與眾不同的聲音，他們靠發出這種聲音互相交流。
當海豚睡覺時，它們處于半驚醒狀態，每次只休息大腦的一半。它們會盡力幫助生病或受傷的海豚；在遇到危險時，它們會相互協助。
正是因為這些及其他類似于人的特性，人們對海豚有著特殊的感情。